Effects of Nitrogen Application on Maize Root in Soil Microbial Flora

Effects of 3 nitrogen application on the amount of cultivable soil bacteria,fungi and actinomycetes both in rhizosphere of maize under different cultural modes were investigated by using plate culture method.The results showed that the amount of soil bacteria and actinomycetes in maize rhizosphere under plastic file mulching and amount of fungi under straw mulching increased after applying nitrogen.The amount of soil microorganisms in maize rhizosphere were effected by maize root,but the amount of soil microorganisms in bulk soil of maize were influenced by using nitrogen.Difference of soil bacteria and fungi number between maize rhizosphere and bulk soil of maize were shortened by using nitrogen under conventional planting mode,but the difference of soil actinomycetes number between maize rhizosphere and bulk soil of maize were augmented by using nitrogen.And differences of soil micro-organisms number between maize rhizosphere and bulk soil of maize were shortened by using nitrogen under mulching modes.Generally speaking,the amount of soil microorganisms in rhizosphere were higher than those in bulk soil of maize,but it was contrary on soil fungi under plastic file mulching and conventional mode and on soil bacteria under strawmulching when applied much nitrogen(240 kg/ha).